Effect of Plasma Treatment (He/CH4) on Glass Surface for the Reduction of Powder Flux Adhesion in the Spray Drying Process

A 50Hz glow discharge He/CH₄plasma was generated and applied for the modification of glass surface to reduce powder adhesion on the wall of spray dryer. The hydrophobicity of the glass samples determined by the water droplet contact angle and adhesion weight on glass, dependent on the CH₄flow rate and plasma exposure time. There was a peak that appeared at 1470 cm^-1on the surface of treated glass indicating the presence of CH₃groups from ATR-FTIR data. Surface morphology analysis using scanning electron microscopy (SEM) showed changes of roughness in the surface-treated glass. The presence of alkyl group (CH₃) that deposited on the glass surface is one of the factors that contribute to the increase in the surface roughness. The surface roughness will reflect the value of contact angle where hydrophobic surface are rougher compared to hydrophilic surface. The plasma treatment could enhance the value of the contact angle and thus reduced the adhesion on the spray dryer glass surface.